The overarching goal of this project is to elucidate the role of ADAM10 in central nervous system myelination. Specifically, this study will examine ADAM10 in oligodendrocyte progenitor cells (OPs) during post-natal subcortical white matter (SCWM) development and following injury. My overall hypothesis is that ADAM10 regulates lineage progression in OPs, and that genetic deletion of ADAM10 allows for OP differentiation, leading to enhanced myelination. I also hypothesize that ADAM10 acts through the Wnt signaling pathway to modulate oligodendrocyte (OL) linage progression. I will thoroughly characterize ADAM10 expression in OL lineage cells during SCWM development, demyelination and remyelination using fluorescent reporter mice. To correlate ADAM10 expression with activity, I will use a sheddase assay with purified OL lineage cells obtained at the same time points as selected for the characterization analysis. For this project, I have generated a mouse that allows for temporal genetic deletion of ADAM10 specifically in OPs (PDGFRa- Cre:ADAM10fl/fl:Rosa-YFP mice). Using this line, I will ablate ADAM10 expression during development and following injury and analyze cell survival and OL lineage progression. I will also directly examine the myelin in PDGFRa-Cre:ADAM10fl/fl mice at the ultra-structural level using electron microscopy analysis. Further, I will perform WB and qPCR analysis of SCWM samples to determine changes in Wnt pathway components and downstream targets following deletion of ADAM10 at developmental and remyelination time points. To determine if ADAM10 primarily signals through the Wnt pathway, I will overexpress -catenin in ADAM10 deficient OPs in vitro and in vivo and analyze lineage progression using antibodies specific for OL lineage cells. Given that OPs have been shown to be distributed throughout the adult brain, they remain an attractive therapeutic target. My findings will uncover novel mechanisms at play in OPs during white matter development and injury, and may assist in the design of new treatments aimed at enhancing remyelination and reducing the long term functional deficits associated with demyelinating disorders.